Operating method of storage device

ABSTRACT

An operation method a storage device including a nonvolatile memory and a memory controller configured to control the nonvolatile memory is provided. The operation method includes erasing memory cells of the nonvolatile memory using the memory controller and prohibiting an erase of the erased memory cells for a critical time using the memory controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 of Korean Patent Application No. 10-2014-0180347, filed onDec. 15, 2014, the entire contents of which are hereby incorporated byreference.

BACKGROUND

The present disclosure relates to a semiconductor memory, and moreparticularly, to an operating method of a storage device.

A storage device is a device storing data according to a control of ahost device such as a computer, a smart phone, a smart pad, etc. Astorage device includes a device storing data in a magnetic disk such asa HDD (hard disk drive) and a device storing data in a semiconductormemory, in particular, a nonvolatile memory such as a SSD (solid statedrive), a memory card, etc.

A nonvolatile memory includes a ROM (read only memory), a PROM(programmable ROM), an EPROM (electrically programmable ROM), an EEPROM(electrically erasable and programmable ROM), a flash memory, a PRMA(phase-change RAM), a MRAM (magnetic RAM), a RRAM (resistor RAM), a FRAM(ferroelectric RAM), etc.

As a semiconductor manufacturing technology develops, high integrationand large capacity of a storage device have been achieved continuously.High integration of a storage device reduces a production cost of thestorage device. However, as a scale of the storage device is reduced anda structure of the storage device is changed because of high integrationof the storage device, various problems that were not found before arefound. Various problems being newly found may damage data stored in thestorage device and thereby reliability of the storage device may bedegraded. A method and a device that can improve reliability of thestorage device are continuously demanded.

SUMMARY

Example embodiments of inventive concepts relate to an operation methodof a storage device including a nonvolatile memory and a memorycontroller configured to control the nonvolatile memory. The operationmethod may include erasing memory cells of the nonvolatile memory usingthe memory controller; and prohibiting an erase of the erased memorycells for a critical time using the memory controller.

In example embodiments, the prohibiting the erase of the erased memorycells for the critical time may include setting at least some memorycells among the erased memory cells to store valid data, managing atable to indicate valid data is stored in the at least some memorycells, and releasing the at least some memory cells after the criticaltime has elapsed.

In example embodiments, the memory controller may be configured toselect the memory cells as an erase target when valid data is not storedin the memory cells.

In example embodiments, the prohibiting the erase of the erased memorycells for the critical time may include collecting information of memoryblocks being erased among memory blocks of the nonvolatile memory, andperiodically registering the information collected in a slot of aninternal table together with an initial count according to a period.Each of the erased memory blocks may be virtually set to store validdata.

In example embodiments, the prohibiting the erase of the erased memorycells for the critical time may further include periodically reducingcounts corresponding to the slots of the interval table according to theperiod.

In example embodiments, the prohibiting the erase of their race memorycells for the critical time may further include periodically releasinginformation of a slot have an account which reaches a threshold valueamong the slots of the interval table according to the period.

In example embodiments, the prohibiting the erase of the race memorycells for the critical time may further include periodically releasingvirtual settings of memory blocks corresponding to a slot have anaccount which reaches a threshold value among the slots of the intervaltable according to the period.

In example embodiments, the prohibiting the erase of the erased memorycells for the critical time may further include mapping at least a partof physical addresses of each of the erased memory blocks to a logicaladdress of an out-of-range area of a logical address of the storagedevice.

In example embodiments, the method may further include storing theinterval table in the nonvolatile memory before power-off.

In example embodiments, the method may further include reading theinterval table from the nonvolatile memory when power is turned on.

Example embodiments of inventive concepts also relate to an operationmethod of a storage device including a nonvolatile memory and a memorycontroller configured to control the nonvolatile memory. The operationmethod may include programming memory cells of the nonvolatile memoryusing the memory controller; and prohibiting an erase of the programmedmemory cells for critical time.

In example embodiments, the prohibiting the erase of the programmedmemory cells for the critical time may include setting at least somememory cells among the programmed memory cells to store valid data,managing the table to indicate valid data is stored in at least somememory cells, and releasing the setting of at least some memory cellsafter the critical time has elapsed.

In example embodiments, the prohibiting the erase of the program memorycells for the critical time may include collecting information of memoryblocks being programmed among memory blocks of the nonvolatile memory,and periodically registering the information being collected in a slotof an interval table together with an initial count according to aperiod. Each of the program memory blocks may be virtually set to storedata.

In example embodiments, the collecting the information of memory blocksbeing programmed may include collecting information of memory blocks inwhich last memory cells are programmed according to a program order ofeach memory block.

In example embodiments, the collecting the information memory box beingprogrammed may include collecting information memory blocks in whichfirst memory cells are programmed according to a program order of eachmemory block.

According to example embodiments, an operation method of a storagedevice including a nonvolatile memory and a memory controller configuredto control the nonvolatile memory is provided. The nonvolatile memoryincludes a plurality of memory cells. The operation method includeserasing memory cells in one of a plurality of erase operation units ofthe nonvolatile memory using the memory controller; and at least one of:(i) excluding the memory cells in the one of the plurality of eraseoperation units as an available erase target for a critical period oftime using the memory controller, the critical period of time beingbased on a time elapsed since the memory cells in the one of theplurality of erase operation units were last erased; and (ii)programming at least some of the memory cells in the one of theplurality of erase operations units and inhibiting the memory cells inthe one of the plurality of erase operation units from being erased fora critical length of time using the memory controller, the criticallength of time being based on a time elapsed since the at some of thememory cells in the one of the plurality of erase operation units werelast programmed.

In example embodiments, the memory cells in the nonvolatile memory maybe organized into a plurality of blocks. The memory blocks may eachinclude a plurality of physical pages. The at least one of excluding thememory cells in the one of the plurality of erase operation units as theavailable erase target and programming at least some of the memory cellsin the one of the plurality of erase operation units and inhibiting thememory cells in the one of the plurality of erase operation units frombeing erased from the critical length of time may include managing atable using the memory controller that maps logical page addresses tothe physical pages of the plurality of memory blocks, mapping a virtualpage to at least one of the physical pages included in the one of aplurality of erase operation units of the nonvolatile memory after theerasing the one of a plurality of erase operation units of thenonvolatile memory, removing the virtual page mapping to the at leastone of the physical pages included in the one of the plurality of eraseoperation units if one of the critical period of time and the criticallength of time has elapsed since the mapping the virtual page, andprohibiting the at least one of the plurality of erase operation unitsfrom being erased using the memory controller if any one of the physicalpages included in the at least one of the plurality of erase operationunits is mapped to the virtual page.

In example embodiments, the at least one of excluding the memory cellsin the one of the plurality of erase operation units as the availableerase target for the critical period of time using the memory controllerand programming the at least some of the memory cells in the one of theplurality of erase operations units and inhibiting the memory cells inthe one of the plurality of erase operation units from being erased forthe critical length of time using the memory controller may be theexcluding the memory cells in the one of the plurality of eraseoperation units as the available erase target for the critical period oftime using the memory controller.

In example embodiments, the at least one of excluding the memory cellsin the one of the plurality of erase operation units as the availableerase target for the critical period of time using the memory controllerand the programming the at least some of the memory cells in the one ofthe plurality of erase operations units and inhibiting the memory cellsin the one of the plurality of erase operation units from being erasedfor the critical length of time using the memory controller may be theprogramming the at least some of the memory cells in the one of theplurality of erase operations units and inhibiting the memory cells inthe one of the plurality of erase operation units from being erased forthe critical length of time using the memory controller.

In example embodiments, the memory cells in the nonvolatile memory maybe organized into a plurality of blocks. Each one of the plurality ofblocks may include a plurality of strings. Each one of the strings mayinclude a number of the memory cells stacked on top of each other in avertical direction between a ground selection transistor and a stringselection transistor.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other features of inventive concepts will be apparentfrom the more particular description of non-limiting embodiments ofinventive concepts, as illustrated in the accompanying drawings in whichlike reference characters refer to like parts throughout the differentviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating principles of inventive concepts. In thedrawings:

FIG. 1 is a block diagram illustrating a storage device in accordancewith example embodiments of inventive concepts.

FIG. 2 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.

FIG. 3 is a block diagram illustrating a nonvolatile memory inaccordance with example embodiments of inventive concepts.

FIG. 4 is a circuit illustrating a memory block in accordance withexample embodiments of inventive concepts.

FIG. 5 is a flow chart illustrating an example of a method ofprohibiting an erase of memory cells according to example embodiments ofinventive concepts.

FIG. 6 is a flow chart illustrating an example of a method of releasinga virtual valid according to example embodiments of inventive concepts.

FIG. 7 illustrates states of memory blocks.

FIG. 8 illustrates mapping information of memory blocks.

FIG. 9 is a timing diagram illustrating an example that memory blocksare erased with the lapse of time.

FIGS. 10 through 18 illustrate a change of tables according to thetiming diagram of FIG. 9.

FIG. 19 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.

FIG. 20 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.

FIG. 21 is a block diagram illustrating a memory controller inaccordance with example embodiments of inventive concepts.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments of inventive concepts will be described more fullyhereinafter with reference to the accompanying drawings, in which someexample embodiments are shown. Example embodiments of inventive conceptsmay, however, be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of inventive concepts to thoseskilled in the art. In the drawings, the size, thicknesses, and relativesizes of layers and regions may be exaggerated for clarity. Like numbersrefer to like elements throughout.

Example embodiments will now be described more fully with reference tothe accompanying drawings, in which some example embodiments are shown.Example embodiments, may, however, be embodied in many different formsand should not be construed as being limited to the embodiments setforth herein; rather, these example embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of example embodiments of inventive concepts to those of ordinaryskill in the art. In the drawings, the thicknesses of layers and regionsare exaggerated for clarity. Like reference characters and/or numeralsin the drawings denote like elements, and thus their description may beomitted.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements or layers should be interpreted in a likefashion (e.g., “between” versus “directly between,” “adjacent” versus“directly adjacent,” “on” versus “directly on”). As used herein the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections. These elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof. Expressions such as “atleast one of,” when preceding a list of elements, modify the entire listof elements and do not modify the individual elements of the list.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of exampleembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle may have rounded or curved features and/or a gradient ofimplant concentration at its edges rather than a binary change fromimplanted to non-implanted region. Likewise, a buried region formed byimplantation may result in some implantation in the region between theburied region and the surface through which the implantation takesplace. Thus, the regions illustrated in the figures are schematic innature and their shapes are not intended to illustrate the actual shapeof a region of a device and are not intended to limit the scope ofexample embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined incommonly-used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

Although corresponding plan views and/or perspective views of somecross-sectional view(s) may not be shown, the cross-sectional view(s) ofdevice structures illustrated herein provide support for a plurality ofdevice structures that extend along two different directions as would beillustrated in a plan view, and/or in three different directions aswould be illustrated in a perspective view. The two different directionsmay or may not be orthogonal to each other. The three differentdirections may include a third direction that may be orthogonal to thetwo different directions. The plurality of device structures may beintegrated in a same electronic device. For example, when a devicestructure (e.g., a memory cell structure or a transistor structure) isillustrated in a cross-sectional view, an electronic device may includea plurality of the device structures (e.g., memory cell structures ortransistor structures), as would be illustrated by a plan view of theelectronic device. The plurality of device structures may be arranged inan array and/or in a two-dimensional pattern.

FIG. 1 is a block diagram illustrating a storage device in accordancewith example embodiments of inventive concepts. Referring to FIG. 1, astorage device 100 includes a nonvolatile memory 110, a memorycontroller 120 and a RAM 130.

The nonvolatile memory 110 can perform write, read and erase operationsunder the control of the memory controller 120. The nonvolatile memory110 can exchange first data DATA1 with the memory controller 120. Forexample, the nonvolatile memory 110 can receive the first data DATA1from the memory controller 120 and write the first data DATA1 into thenonvolatile memory 110. The nonvolatile memory 110 can perform a readoperation and can output the first data DATA1 read to the memorycontroller 120.

The nonvolatile memory 110 can receive a first command CMD1 and a firstaddress ADDR1 from the memory controller 120. The nonvolatile memory 110can exchange a control signal CTRL with the memory controller 120. Forexample, the nonvolatile memory 110 can receive at least one of a chipselect signal /CE selecting at least one semiconductor chip among aplurality of semiconductor chips constituting the nonvolatile memory110, a command latch enable signal CLE indicating that a signal beingreceived from the memory controller 120 is the first command CMD1, aread enable signal /RE which is generated by the memory controller 120in a read operation and is periodically toggled to be used to adjust thetiming, a write enable signal /WE being activated by the memorycontroller 120 when the first command CMD1 or the first address ADDR1 istransmitted, a write protection signal /WP being activated by the memorycontroller 120 to protect an unwanted write or erase when power supplyis changed, a data strobe signal DQS which is generated by the memorycontroller 120 in a write operation and is periodically toggled to beused to adjust an input sync of the first data DATA1 from the memorycontroller 120. The nonvolatile memory 110 can output at least one of aready and busy signal R/Nb indicating whether the nonvolatile memory 110is performing a program, erase or read operation and a data strobesignal DQS which is generated from the read enable signal /RE by thenonvolatile memory 110 and is periodically toggled to be used to adjustan output sync of the first data DATA1 to the memory controller 120.

The first data DATA1, the first address ADDR1 and the first command CMD1can be communicated with the memory controller 120 through a firstchannel CH1. The first channel CH1 may be an input/output channel. Thecontrol signal CTRL can be communicated with the memory controller 120through a second channel CH2. The second channel CH2 may be a controlchannel.

The nonvolatile memory 110 may include a flash memory. However, thenonvolatile memory 110 is not limited to include the flash memory. Thenonvolatile memory 110 may include at least one of various nonvolatilememories such as a PRAM (phase-change RAM), a MRAM (magnetic RAM), aRRAM (resistive RAM), a FeRAM (ferroelectric RAM), etc.

The memory controller 120 is configured to control the nonvolatilememory 110. For example, the memory controller 120 can control so thatthe nonvolatile memory 110 performs a write, read or erase operation.The memory controller 120 can exchange the first data DATA1 and thecontrol signal CTRL with the nonvolatile memory 110 and output the firstcommand CMD1 and the first address ADDR1 to the nonvolatile memory 110.

The memory controller 120 can control the nonvolatile memory 110 underthe control of an external host device (not shown). The memorycontroller 120 can exchange second data DATA2 with the host device andreceive a second command CMD2 and a second address ADDR2 from the hostdevice.

The memory controller 120 can exchange the first data DATA1 with thenonvolatile memory 110 by a first unit (for example, time unit or dataunit) and exchange the second data DATA2 with the host device by asecond unit (for example, time unit or data unit) different from thefirst unit.

The memory controller 120 can exchange the first data DATA1 with thenonvolatile memory 110 according to a first format and transmit thefirst command CMD1 and the first address ADDR1 to the nonvolatile memory110. The memory controller 120 can exchange the second data DATA2 withthe host device according to a second format different from the firstformat and receive the second command CMD2 and the second address ADDR2from the host device.

The memory controller 120 can use the RAM 130 as a buffer memory, acache memory or an operation memory. For example, the memory controller120 can receive the second data DATA2 from the host device, store thereceived second data DATA2 in the RAM 130 and write the second dataDATA2 stored in the RAM 130 in the nonvolatile memory 110 as the firstdata DATA1. The memory controller 120 can receive the first data DATA1from the nonvolatile memory 110, store the received first data DATA1 inthe RAM 130 and output the first data DATA1 stored in the RAM 130 to thehost device as the second data DATA2. The memory controller 120 canstore data read from the nonvolatile memory 110 in the RAM 130 and writethe data stored in the RAM 130 in the nonvolatile memory 110 again.

The memory controller 120 can store data or code needed to manage thenonvolatile memory 110 in the RAM 130. For example, the memorycontroller 120 can read data or code needed to manage the nonvolatilememory 110 from the nonvolatile memory 110 and load the data or the codein the RAM 130 to drive it.

The memory controller 120 includes a time counter 128 and a tablemanager 129. The time counter 128 can periodically generate an interruptsignal according to a desired (and/or alternatively predetermined)period. For example, the time counter 128 can periodically generate aninterrupt signal in response to a clock signal being generated from theinside of the storage device 100 or a clock signal being received froman external host device.

The table manager 129 is configured to manage tables 131 stored in theRAM 130. For example, the table manager 129 can manage the tables 131 inresponse to an interrupt signal being generated by the time counter 128.According to a desired (and/or alternatively predetermined) schedule,the table manager 129 can backup or flush the tables 131 stored in theRAM 130 to the nonvolatile memory 110 periodically or when power isturned off. When power is turned on, the table manager 129 can read thetables 131 from the nonvolatile memory 110 to store the table 131 in theRAM 130.

The RAM 130 may include at least one of various random access memoriessuch as a DRAM (dynamic RAM), a SRAM (static RAM), a SDRAM (synchronousDRAM), a PRAM (phase change RAM), a MRAM (magnetic RAM), a RRAM(resistive RAM), a FeRAM (ferroelectric RAM), etc. The RAM 130 can storethe tables 131.

To reduce an overhead that an erase operation occurs in the nonvolatilememory 110, the storage device 100 can perform an address mapping. Forexample, when an overwrite is requested from an external host, thestorage device 100 can store overwrite-requested data in memory cells ofa free storage space instead of erasing memory cells storing existingdata to store the overwrite-requested data in the erased memory cells.The memory controller 120 can drive a FTL (flash translation layer)mapping a logical address being used in an external host device and aphysical address being used in the nonvolatile memory 110 according tothe method described above. For example, the second address ADDR2 may bea logical address and the first address ADDR1 may be a physical address.

The storage device 100 can perform write, read or erase of dataaccording to a request of a host device. The storage device 100 mayinclude a SSD (solid state drive) or a HDD (hard disk drive). Thestorage device 100 may include memory cards such as a personal computermemory card international association (PCMCIA) card, a compact flash(CF) card, a smart media card (SM, SMC), a memory stick, a multimediacard (MMC, RS-MMC, MMCmicro), a SD card (SD, miniSD, microSD, SDHC), auniversal flash memory device (UFS), etc. The storage device 100 mayinclude a mounted memory such as an eMMC (embedded multimedia card), aUFS, a PPN (perfect page new), etc.

FIG. 2 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.Referring to FIGS. 1 and 2, in an operation S110, the memory controller120 erases memory cells of the nonvolatile memory 110. In an operationS120, the memory controller 120 prohibits an erasure of erased memorycells of the nonvolatile memory 110 for critical time TCR.

If a time interval at which memory cells of the nonvolatile memory 110are erased is shorter than the critical time TCR, reliability of thememory cells is degraded. The storage device 100 in accordance withexample embodiments of inventive concepts improves reliability of thenonvolatile memory 110 by prohibiting an erase of erased memory cellsfor the critical time TCR.

FIG. 3 is a block diagram illustrating a nonvolatile memory inaccordance with example embodiments of inventive concepts. Referring toFIGS. 1 and 3, the nonvolatile memory 110 includes a memory cell array111, an address decoder circuit 113, a page buffer circuit 115, a datainput/output circuit 117, and a control logic circuit 119.

The memory cell array 111 includes a plurality of memory blocksBLK1˜BLKz. Each memory block includes a plurality of memory cells. Eachmemory block can be connected to the address decoder circuit 113 throughat least one ground select line GSL, a plurality of word lines WL and atleast one string select line SSL. Each memory block can be connected tothe page buffer circuit 115 through a plurality of bit lines BL. Thememory blocks BLK1˜BLKz can be connected to the plurality of bit linesBL in common. Memory cells of the memory blocks BLK1˜BLKz may have thesame structure. Each memory block may be an erase operation unit. Memorycells of the memory cell array 111 may be erased by a memory block unit.Memory cells that belong to one memory block may be erased at the sametime. In example embodiments, each memory block may be divided into aplurality of sub blocks and each sub block may be an erase operationunit.

The address decoder circuit 113 is connected to the memory cell array111 through a plurality of ground select lines GSL, a plurality of wordlines WL and a plurality of string select lines SSL. The address decodercircuit 113 operates according to a control of the control logiccircuit. The address decoder circuit 113 can receive the first addressADDR1 from the memory controller 120. The address decoder circuit 113decodes the received first address ADDR1 and can control voltages beingapplied to the word lines WL according to the decoded address.

For example, in a program operation, the address decoder circuit 113 mayapply a program voltage VPGM to a selected word line of a selectedmemory block indicated by the first address ADDR1 and apply a passvoltage VPASS to unselected word lines of the selected memory block. Ina read operation, the address decoder circuit 113 may apply a selectread voltage VRD to a selected word line of a selected memory blockindicated by the first address ADDR1 and apply an unselect read voltageVREAD to unselected word lines of the selected memory block. In an eraseoperation, the address decoder circuit 113 may apply an erase voltage(for example, a ground voltage) to word lines of a selected memory blockindicated by the first address ADDR1.

The page buffer circuit 115 is connected to the memory cell array 111through a plurality of bit lines BL. The page buffer circuit 115 isconnected to the data input/output circuit 117 through a plurality ofdata lines DL. The page buffer circuit 115 operates under the control ofthe control logic circuit 119.

The page buffer circuit 115 can store data to be programmed in memorycells of the memory cell array 111 or data being read from the memorycells. In a program operation, the page buffer circuit 115 can storedata to be programmed in the memory cells. On the basis of the storeddata, the page buffer circuit 115 can bias a plurality of bit lines BL.In a program operation, the page buffer circuit 115 can function as awrite driver. In a read operation, the page buffer circuit 115 can sensevoltages of the bit lines BL and store a sensing result. In a readoperation, the page buffer circuit 115 can function as a senseamplifier.

The data input/output circuit 117 is connected to the page buffercircuit 115 through the plurality of data lines DL. The datainput/output circuit 117 can exchange the first data DATA1 with thememory controller 120.

The data input/output circuit 117 can temporarily store the first dataDATA1 being received from the memory controller 120. The datainput/output circuit 117 can transmit the stored data to the page buffercircuit 115. The data input/output circuit 117 can temporarily storedata being transmitted from the page buffer circuit 115. The datainput/output circuit 117 can transmit the stored data to the memorycontroller 120. The data input/output circuit 117 can function as abuffer memory.

The control logic circuit 119 receives the first command CMD1 from thememory controller 120. The control logic circuit 119 decodes thereceived first command CMD1 and can control an overall operation of thenonvolatile memory 110 according to the decoded command.

In a read operation, the control logic circuit 119 can generate a datastrobe signal DQS from a read enable signal /RE among the receivedcontrol signals CTRL and output it. In a write operation, the controllogic circuit 119 can operate using the data strobe signal DQS among thereceived control signals CTRL.

FIG. 4 is a circuit illustrating a memory block BLKa in accordance withexample embodiments of inventive concepts. Referring to FIG. 4, thememory block BLKa includes a plurality of cell strings CS11˜CS21 andCS12˜CS22. The cell strings CS11˜CS21 and CS12˜CS22 can be arrangedalong a row direction and a column direction to from rows and columns.

For example, the cell strings CS11 and CS12 arranged along the rowdirection form a first row and the cell strings CS21 and CS22 arrangedalong the row direction form a second row. The cell strings CS11 andCS21 arranged along the column direction form a first column and thecell strings CS12 and CS22 arranged along the column direction form asecond column.

Each cell string may include a plurality of cell transistors. The celltransistors include ground select transistors GSTa and GSTb, memorycells MC1˜MC6, and string select transistors SSTa and SSTb. The groundselect transistors GSTa and GSTb, the memory cells MC1˜MC6, and thestring select transistors SSTa and SSTb of each cell string may bestacked in a direction perpendicular to a plane (for example, a plane ona substrate of the memory block BLKa) on which the cell stringsCS11˜CS21 and CS12˜0522 are arranged along rows and columns.

The cell transistors may be charge trap type transistors havingthreshold voltages that are changed depending on a charge amount trappedin an insulating layer.

The lowermost ground select transistor GSTa may be connected to a commonsource line CSL in common.

The ground select transistors GSTa and GSTb of the cell stringsCS11˜CS21 and CS12˜0522 may be connected to a ground select line GSL incommon.

Ground select transistors having the same height (or order) areconnected to the same ground select line and ground select transistorshaving different heights (or orders) are connected to the differentground select lines. For example, the ground select transistors GSTahaving a first height may be connected to a first ground select line incommon and the ground select transistors GSTb having a second height maybe connected to a second ground select line in common.

Ground select transistors of the same row are connected to the sameground select line and ground select transistors of different rows maybe connected to different ground select lines. For example, the groundselect transistors GSTa and GSTb of the cell strings CS11 and CS12 of afirst row may be connected to the first ground select line and theground select transistors GSTa and GSTb of the cell strings CS21 andCS22 of a second row may be connected to the second ground select line.

Memory cells located at the same height (or order) from a substrate (orground select transistors GST) may be connected to one word line incommon and memory cells located at different heights (or orders) fromthe substrate (or ground select transistors GST) may be connected todifferent word lines WL1˜WL6. For example, memory cells MC1 areconnected to the word line WL1 in common. Memory cells MC2 are connectedto the word line WL2 in common. Memory cells MC3 are connected to theword line WL3 in common. Memory cells MC4 are connected to the word lineWL4 in common. Memory cells MC5 are connected to the word line WL5 incommon. Memory cells MC6 are connected to the word line WL6 in common.

In the first string select transistors SSTa of the same height (ororder) of the cell strings CS11˜CS21 and CS12˜CS22, the first stringselect transistors SSTa of different rows are connected to differentstring select lines SSL1 a˜SSL2 a respectively. For example, the firststring select transistors SSTa of the cell strings CS11 and CS12 areconnected to the string select line SSL1 a in common. The first stringselect transistors SSTa of the cell strings CS21 and CS22 are connectedto the string select line SSL2 a in common.

In the second string select transistors SSTb of the same height (ororder) of the cell strings CS11˜CS21 and CS12˜CS22, the second stringselect transistors SSTb of different rows are connected to differentstring select lines SSL1 b˜SSL2 b respectively. For example, the secondstring select transistors SSTb of the cell strings CS11 and CS12 areconnected to the string select line SSL1 b in common. The second stringselect transistors SSTb of the cell strings CS21 and CS22 are connectedto the string select line SSL2 b in common.

That is, cell strings of different rows are connected to differentstring select lines. String select transistors of the same height (ororder) of cell strings of the same row are connected to the same stringselect line. String select transistors of different heights (or orders)of cell strings of the same row are connected to different string selectlines.

String select transistors of cell strings of the same row may beconnected to one string select line in common. For example, the stringselect transistors SSTa and SSTb of the cell strings CS11 and CS12 ofthe first row may be connected to one string select line in common. Thestring select transistors SSTa and SSTb of the cell strings CS21 andCS22 of the second row may be connected to one string select line incommon.

Columns of the cell strings CS11˜CS21 and CS12˜CS22 are connected todifferent bit lines BL1 and BL2 respectively. For example, the stringselect transistors SSTb of the cell strings CS11˜0521 of the firstcolumn may be connected to the bit line BL1 in common. The string selecttransistors SSTb of the cell strings C512˜0522 of the second column maybe connected to the bit line BL2 in common.

The cell strings CS11 and CS12 may form a first plane. The cell stringsCS21 and CS22 may form a second plane.

In the memory block BLKa, write and read operations may be performed bya row unit. For example, one plane of the memory block BLKa may beselected by the string select lines SSL1 a, SSL1 b, SSL2 a and SSL2 b.When a turn-on voltage is supplied to the string select lines SSL1 a andSSL1 b and a turn-off voltage is supplied to the string select linesSSL2 a and SSL2 b, the cell strings CS11 and CS12 of the first plane areconnected to the bit lines BL1 and BL2. That is, the first plane isselected. When a turn-on voltage is supplied to the string select linesSSL2 a and SSL2 b and a turn-off voltage is supplied to the stringselect lines SSL1 a and SSL1 b, the cell strings CS21 and CS22 of thesecond plane are connected to the bit lines BL1 and BL2. That is, thesecond plane is selected. In the selected plane, one row of the memorycells MC may be selected by the word lines WL1˜WL6. In the selectedplane, a write or read operation may be performed.

In the memory block BLKa, an erase operation may be performed by amemory block unit or a sub block unit. When an erase operation isperformed by a memory block unit, all the memory cells MC of the memoryblock BLKa may be erased at the same time according to one eraserequest. When an erase operation is performed by a sub memory blockunit, a part of the memory cells MC of the memory block BLKa may beerased at the same time according to one erase request and the otherpart of the memory cells MC may be erase-prohibited. A low voltage (forexample, a ground voltage) is supplied to a word line connected tomemory cells being erased and a word line connected to erase-prohibitedmemory cells may be floated.

The memory block BLKa illustrated in FIG. 4 is illustrative. Exampleembodiments of inventive concepts are not limited to the memory blockBLKa illustrated in FIG. 4. For example, the number of cell strings mayincrease or decrease. As the number of cell strings is changed, thenumber of string select lines or ground select lines connected to rowsof the cell strings and the number of cell strings connected to one bitline may also be changed.

The number of columns of the cell string may increase or decrease. Asthe number of columns of the cell string is changed, the number of bitlines connected to columns of the cell strings and the number of cellstrings connected to one string select line may also be changed.

Heights of the cell strings may increase or decrease. For example, thenumber of ground select transistors, memory cells or string selecttransistors being stacked on each of the cell strings may be increase ordecrease.

Memory cells MC that are connected to one word line and belong to onerow may correspond to at least three pages. For example, k (k is apositive integer greater than 2) number of bits can be programmed in onememory cell. In the memory cells MC that are connected to one word lineand belong to one row, k number of bits being programmed in each of thememory cells MC may form k number of pages.

In example embodiments, a nonvolatile memory may be embodied to includea three dimensional (3D) memory array. The 3D memory array may bemonolithically formed on a substrate (e.g., semiconductor substrate suchas silicon, or semiconductor-on-insulator substrate). The 3D memoryarray may include two or more physical levels of memory cells having anactive area disposed above the substrate and circuitry associated withthe operation of those memory cells, whether such associated circuitryis above or within such substrate. The layers of each level of the arraymay be directly deposited on the layers of each underlying level of thearray.

The following patent documents, which are hereby incorporated byreference in their entirety, describe suitable configurations forthree-dimensional memory arrays, in which the three-dimensional memoryarray is configured as a plurality of levels, with word lines and/or bitlines shared between levels: U.S. Pat. Nos. 7,679,133; 8,553,466;8,654,587; 8,559,235; and US Pat. Pub. No. 2011/0233648.

In example embodiments, the 3D memory array may include vertical NANDstrings that are vertically oriented such that at least one memory cellis located over another memory cell. The at least one memory cell maycomprise a charge trap layer. Each vertical NAND string may furtherinclude at least one select transistor located over memory cells. The atleast one select transistor may have the same structure with the memorycells and may be formed monolithically together with the memory cells.

FIG. 5 is a flow chart illustrating example of a method (operation S120)of prohibiting an erase of memory cells according to example embodimentsof inventive concepts. Referring to FIGS. 1, 3, 4 and 5, in an operationS210, the memory controller 120, after erasing the memory block BLKa,sets at least one page that belongs the memory block BLKa as a virtualvalid. For example, the tables 131 may include information about memoryblocks BLK1˜BLKz. The table manager 129 can manage the tables 131 toindicate that valid data is stored in at least one page of the memoryblock BLKa. For example, the table manager 129 can set a virtual validat the same time erasing the memory block BLKa, immediately beforeerasing the memory block BLKa or immediately after erasing the memoryblock BLKa.

According to a desired (and/or alternatively predetermined) schedule ora request of an external host device, the memory controller 120 canselect a memory block to be erased among the memory blocks BLK1˜BLKz ofthe nonvolatile memory 110. The memory controller 120 is configured toselect a memory block to be erased among memory blocks not storing validdata. Thus, if it is set that valid data is stored in at least one pageof the memory block BLKa, the memory block BLKa may be excluded from anerase target.

In an operation S220, the memory controller 120 can release a virtualvalid after the critical time TCR. For example, the table manager 129can determine whether critical time TCR has passed after a virtual validis set in the memory block BLKa on the basis of time information beingoutput from the time counter 128. After it is determined that criticaltime TCR has passed, the table manager 129 can release the virtual validset in the memory block BLKa.

If the virtual valid is released, the memory block BLKa may be selectedas an erase target. For example, after the memory block BLKa is erased,data may be programmed in the memory block BLKa. Data programmed in thememory block BLKa may be invalidated according to a request of anexternal host device or an internal schedule. If the virtual valid ofthe memory block BLKa is released and data programmed in the memoryblock BLKa is set as invalid data, it is distinguished that the memoryblock BLKa does not store valid data. Thus, the memory block BLKa may beselected as an erase target.

FIG. 6 is a flow chart illustrating an example of a method (S220) ofreleasing a virtual valid according to example embodiments of inventiveconcepts. Referring to FIGS. 1, 3, 4 and 6, in an operation S305, powermay be supplied to the storage device 100. In the case that the tables131 is backed up or flushed to the nonvolatile memory 110, the tables131 may be loaded in the RAM 130 from the nonvolatile memory 110 whenpower is supplied to the storage device 100.

In an operation S310, the memory controller 120 collects information ofmemory cells being erased. For example, the table manager 129 cancollect information of memory blocks being erased (or other erase unitlike a sub block). The table manager 129 can collect information ofmemory blocks being erased during a desired (and/or alternativelypredetermined) period managed by the time counter 128.

In an operation S315, the memory controller 120 determines whether aperiodical interrupt occurs. For example, it may be determined whetheran interrupt signal is output from the time counter 128.

If an interrupt signal is output, in an operation S320, the memorycontroller 120 registers the collected information in an interval tableIT together with an initial counter. For example, the tables 131 mayinclude the interval table IT. The table manager 129 can registerinformation of the erased memory blocks and the initial counter in theinterval table IT.

In an operation S325, the table manager 129 reduces counters of theinformation previously registered in the interval table IT.

In an operation S330, the table manager 129 determines whetherinformation corresponding to ‘0’ counter exists among the informationregistered in the interval table IT.

If information corresponding to ‘0’ counter exists, in an operationS335, the table manager 129 releases a virtual valid of the informationcorresponding to the ‘0’ counter. For example, the table manager 129 candetect an address of the memory block (or other erase unit like a subblock) from the information corresponding to the ‘0’ counter of theinterval table IT. The table manager 129 can release a virtual valid ofthe memory block corresponding to the detected address.

In an operation S340, the table manager 129 can release informationcorresponding to the ‘0’ counter from the interval table IT.

In an operation S345, if the storage device 100 is not powered off, theoperation S310 is performed again.

The operations S310 through S340 may be repeatedly performed while poweris supplied to the storage device 100. When the memory block BLKa iserased, at least one page of the memory block BLKa is set to a virtualvalid. Information of the memory block BLKa is registered in theinterval table IT. As the operations S310 through S340 are repeated, acounter of the memory block BLKa decreases from the initial counter.Until the counter of the memory block BLKa is reduced to ‘0’, the memoryblock BLKa is erase-prohibited due to the virtual valid.

A first table T1 of FIG. 7 illustrates states of memory blocksBLK1˜BLK4. A second table T2 of FIG. 8 illustrates mapping informationof memory blocks BLK1˜BLK4. Referring to FIGS. 7 and 8, it is assumedthat each of the memory blocks BLK1˜BLK4 has four pages. Pages of thefirst memory block BLK1 corresponds to first through fourth physicalpage addresses PPN1˜PPN4 respectively. Pages of the second memory blockBLK2 corresponds to fifth through eighth physical page addressesPPN5˜PPN8 respectively. Pages of the third memory block BLK3 correspondsto ninth through twelfth physical page addresses PPN9˜PPN12respectively. Pages of the fourth memory block BLK4 corresponds tothirteenth through sixteenth physical page addresses PPN13˜PPN16respectively. For example, the physical page addresses PPN1˜PPN16 maycorrespond to a first address ADDR1 which is transmitted to thenonvolatile memory 110 by the memory controller 120.

The first table T1 may include information about whether valid data isstored in pages of the memory blocks BLK1˜BLK4. It is assumed that eachof the first through sixteenth physical page addresses PPN1˜PPN16 storesvalid data.

The first table T1 may further include information about the number ofpages in which valid data is stored in each of the memory blocksBLK1˜BLK4, that is, a valid count VCNT. It is assumed that the validcounts VCNT of the memory blocks BLK1˜BLK4 are each 4.

The second table T2 includes mapping information between the physicalpage addresses PPN1˜PPN16 and logical page addresses LPN1˜LPN16. Forexample, the memory controller 120 can divide second data DATA2 beingreceived from an external host device into a page unit of thenonvolatile memory 110. The memory controller 120 can convert a secondaddress ADDR2 being received from the nonvolatile memory 110 togetherwith the second data DATA2 into the logical page addresses LPN1˜LPN16.The data divided into a page unit may be related to the logical pageaddresses LPN1˜LPN16. For example, the logical page addresses LPN1˜LPN16can form a user area UA that an external host device identifies as astorage space of the storage device 100.

The memory controller 120 can map the logical page addresses LPN1˜LPN16and the physical page addresses PPN1˜PPN16 to each other. For example,the first through fourth logical page addresses LPN1˜LPN4 may be mappedto the fifth through eighth physical page addresses PPN5˜PPN8. When anexternal host device requests the storage device 100 to access datastored in the first through fourth logical page addresses LPN1˜LPN4, thememory controller 120 can access pages of the nonvolatile memory 110corresponding to the fifth through eighth physical page addressesPPN5˜PPN8 of the second memory block BLK2.

The fifth through eighth logical page addresses LPN5˜LPN8 can be mappedto the ninth through twelfth physical page addresses PPN9˜PPN12 of thethird memory block BLK3 respectively. The ninth through twelfth logicalpage addresses LPN9˜LPN12 can be mapped to the first through fourthphysical page addresses PPN1˜PPN4 of the first memory block BLK1respectively. The thirteenth through sixteenth logical page addressesLPN13˜LPN16 can be mapped to the thirteenth through sixteenth physicalpage addresses PPN13˜PPN16 of the fourth memory block BLK4 respectively.

The first table T1 and the second table T2 are a part of the tables 131and may be managed by the table manager 129.

FIG. 9 is a timing diagram illustrating an example that memory blocksBLK1˜BLK4 are erased with the lapse of time. FIGS. 10 through 18illustrate a change of tables 131 according to the timing diagram ofFIG. 9.

Referring to FIG. 9, first through sixth interrupt signals INT1˜INT6 maybe sequentially generated by the time counter 128. The first throughsixth interrupt signals INT1˜INT6 may be generated at desired (and/oralternatively predetermined) time intervals such as a period PER.

The memory controller 120 can collect information of memory blocks (orother erase units like sub blocks) being erased until the secondinterrupt signal INT2 is generated after the first interrupt signal INT1is generated. For example, the second memory block BLK2 may be erasedbefore the second interrupt signal INT2 is generated after the firstinterrupt signal INT1 is generated. The second memory block BLK2 may beerased after data stored in the second memory block BLK2 becomesinvalid. An example of the tables 131 of when data stored in the secondmemory block BLK2 becomes invalid is illustrated in FIGS. 10 and 11.

Referring to FIGS. 1, 3, 4, 10 and 11, data stored in the second memoryblock BLK2 becomes invalid. If data stored in the second memory blockBLK2 becomes invalid, the table manager 129 can renew or update thefirst table T1 and the second table T2.

For example, in the second table T2, the table manager 129 can deletemappings of the first through fourth logical page addresses LPN1˜LPN4 ofthe second table T2. It may be discriminated that the first throughfourth logical page addresses LPN1˜LPN4 are free storage spaces as shownin FIG. 11.

The table manager 129 can renew the first table T1 to indicate thatinvalid data is stored in the physical page addresses PPN5˜PPN8 of thesecond memory block BLK2 as shown in FIG. 10. The table manager 129 canreduce a valid count VCNT to ‘0’.

Referring to FIG. 9 again, the table manager 129 can renew the tables131 in response to the second interrupt signal INT2. An example that thetables 131 are renewed in response to the second interrupt signal INT2is illustrated in FIGS. 12 and 13.

Referring to FIGS. 1, 3, 4, 9, 12 and 13, as described with reference tothe operation S210 of FIG. 5, the table manager 129 sets at least one ofpages of the second memory block BLK2 as a virtual valid so that thesecond memory block BLK2 is erase-prohibited. For example, the tablemanager 129 can add an OORA (out-of-range area) to the second table T2as shown in FIG. 13. For example, a logical page address LPN of the OORA(out-of-range area) may not belong to the logical page addressesLPN1˜LPN6 of the user area UA of the storage device 100. The logicalpage address LPN of the OORA may be a virtual address which is notdiscriminated as a storage space of the storage device 100.

As the second memory block BLK2 is erased, the table manager 129 can adda seventeenth logical page address LPN17 to the OORA. The table manager129 can map at least one physical page address of the physical pageaddresses PPN5˜PPN6 of the second memory block BLK2, for example, thefifth physical page address PPN5 to the seventeenth logical page addressLPN17 of the OORA. Since the seventeenth logical page address LPN17 doesnot correspond to an actual storage space of the storage device 100, amapping between the seventeenth logical page address LPN17 and the fifthphysical page address PPN5 may be a virtual mapping.

The table manager 129 can also renew the first table T1. For example, asthe fifth physical page address PPN5 of the second memory block BLK2 isvirtually mapped to the seventeenth logical page address LPN17, thetable manager 129 can increase a valid count VCNT of the second memoryblock BLK2 by ‘1’ as shown in FIG. 12. For example, the valid count VCNTof the second memory block BLK2 may be a value that an OV (originalvalue) indicating the number of pages in which valid data is storedamong pages of the second memory block BLK2 is increased by ‘1’ by avirtual valid.

As described with reference to the operation S320 of FIG. 6, the tablemanager 129 can add an interval table IT as a part of the tables 131.For example, the table manager 129 can register the seventeenth logicalpage address LPN17 related to the virtual valid of the second memoryblock BLK2 to the interval table IT together with an initial count, forexample, ‘3’.

After the second memory block BLK2 is erased, data may be programmed inthe second memory block BLK2. For example, the second table T2 may berenewed so that the physical page addresses PPN5˜PPN8 of the secondmemory block BLK2 are mapped to the first through fourth logical pageaddresses LPN1˜LPN4 again. The first table T1 may be renewed to indicatethat valid data is stored in the physical page addresses PPN5˜PPN8 ofthe second memory block BLK2. The time that data is programmed in thesecond memory block BLK2 is not limited and thereby in the first andsecond tables T1 and T2, whether valid data is stored in the physicalpage addresses PPN5˜PPN8 and whether the physical page addressesPPN5˜PPN8 are mapped to the logical page addresses LPN1˜LPN4 areillustrated as don't care.

Referring to FIG. 9 again, the memory controller 120 can collectinformation of memory blocks (or other erase units like sub blocks)being erased until the third interrupt signal INT3 is generated afterthe second interrupt signal INT2 is generated. For example, the firstand fourth memory blocks BLK1 and BLK4 may be erased before the thirdinterrupt signal INT3 is generated after the second interrupt signalINT2 is generated. As described with reference to FIGS. 10 and 11, thefirst and fourth memory blocks BLK1 and BLK4 may be erased after datastored in the first and fourth memory blocks BLK1 and BLK4 becomesinvalid.

The table manager 129 can renew the tables 131 in response to the thirdinterrupt signal INT3. An example that the tables 131 are renewed inresponse to the third interrupt signal INT3 is illustrated in FIGS. 14and 15.

Referring to FIGS. 1, 3, 4, 9, 14 and 15, as described with reference tothe operation S210 of FIG. 5, the table manager 129 sets at least onepage among pages of the first and fourth memory blocks BLK1 and BLK4 asa virtual valid so that the first and fourth memory blocks BLK1 and BLK4are erase-prohibited. For example, the table manager 129 can addeighteenth and nineteenth logical page addresses LPN18 and LPN19 to anOORA (out-of-range area) of the second table T2 as shown in FIG. 15. Thetable manager 129 can map the first and thirteenth physical pageaddresses PPN1 and PPN13 of the first and fourth memory blocks BLK1 andBLK4 to the eighteenth and nineteenth logical page addresses LPN18 andLPN19 of the OORA (out-of-range area) respectively.

The table manager 129 can also renew the first table T1. For example, asthe first and thirteenth physical page addresses PPN1 and PPN13 of thefirst and fourth memory blocks BLK1 and BLK4 are mapped to theeighteenth and nineteenth logical page addresses LPN18 and LPN19, thetable manager 129 can increase a valid count VCNT of the first andfourth memory blocks BLK1 and BLK4 by ‘1’ from an original value OV asshown in FIG. 14.

As described with reference to the operation S320 of FIG. 6, the tablemanager 129 can register the eighteenth and nineteenth logical pageaddresses LPN18 and LPN19 related to the first and fourth memory blocksBLK1 and BLK4 to the interval table IT together with an initial count,for example, ‘3’.

As described with reference to the operation S325 of FIG. 6, the tablemanager 129 can renew the interval table IT so that a count of theseventeenth logical page address LPN17 related to the second memoryblock BLK2 previously registered is reduced.

After the first and fourth memory blocks BLK1 and BLK4 are erased, datamay be programmed in the first and fourth memory blocks BLK1 and BLK4.The time that data is programmed in the first and fourth memory blocksBLK1 and BLK4 is not limited and thereby “don't care” is illustrated inthe first and second tables T1 and T2.

Referring to FIG. 9 again, the memory controller 120 can collectinformation of memory blocks (or other erase units like sub blocks)being erased until the fourth interrupt signal INT4 is generated afterthe third interrupt signal INT3 is generated. For example, the memoryblocks BLK may not be erased before the fourth interrupt signal INT4 isgenerated after the third interrupt signal INT3 is generated.

The table manager 129 can renew the tables 131 in response to the fourthinterrupt signal INT4. An example that the tables 131 is renewed inresponse to the fourth interrupt signal INT4 is illustrated in FIG. 16.

Referring to FIGS. 1, 3, 4, 9 and 16, as described with reference to theoperation S325 of FIG. 6, the table manager 129 can renew the intervaltable IT so that a count of the seventeenth logical page address LPN17related to the second memory block BLK2 previously registered isreduced. The table manager 129 can further renew the interval table ITso that a count of the eighteenth and nineteenth logical page addressesLPN18 and LPN19 related to the first and fourth memory blocks BLK1 andBLK4 previously registered is reduced.

Referring to FIG. 9, the memory controller 120 can collect informationof memory blocks (or other erase units like sub blocks) being eraseduntil the fifth interrupt signal INT5 is generated after the fourthinterrupt signal INT4 is generated. For example, the memory block BLK3may be erased before the fifth interrupt signal INT5 is generated afterthe fourth interrupt signal INT4 is generated. As described withreference to FIGS. 10 and 11, the third memory block BLK3 may be erasedafter the data stored in the third memory block BLK3 becomes invalid.

The table manager 129 can renew the tables 131 in response to the fifthinterrupt signal INT5. An example that the tables 131 is renewed inresponse to the fifth interrupt signal INT5 is illustrated in FIGS. 17and 18.

Referring to FIGS. 1, 3, 4, 9, 17 and 18, as described with reference tothe operation S210 of FIG. 5, the table manager 129 sets at least one ofpages of the third memory block BLK3 as a virtual valid so that thethird memory block BLK3 is erase-prohibited. For example, the tablemanager 129 can add a twentieth logical page address LPN20 to an OORA(out-of-range area) of the second table T2. The table manager 129 canmap the ninth physical page address PPN9 of the third memory block BLK3with the twentieth logical page address LPN20 of the OORA (out-of-rangearea).

The table manager 129 can also renew the first table T1. For example, asthe ninth physical page addresses PPN9 of the third memory block BLK3 ismapped to the twentieth logical page address LPN20, the table manager129 can increase a valid count VCNT of the third memory block BLK3 by‘1’ from an original value OV.

As described with reference to the operation S320 of FIG. 6, the tablemanager 129 can register the twentieth logical page address LPN20related to the third memory block BLK3 to the interval table IT togetherwith an initial count, for example, ‘3’.

As described with reference to the operation S325 of FIG. 6, the tablemanager 129 can renew the interval table IT so that a count of theseventeenth logical page address LPN17 related to the second memoryblock BLK2 previously registered is reduced. The table manager 129 canfurther renew the interval table IT so that a count of the eighteenthand nineteenth logical page addresses LPN18 and LPN19 related to thefirst and fourth memory blocks BLK1 and BLK4 previously registered isreduced.

In the interval table IT, a count of the seventeenth logical pageaddress LPN17 related to the second memory block BLK2 reaches ‘0’. Thus,as described with reference to the operation S335 of FIG. 6, the tablemanager 129 can renew the interval table IT so that a mapping of thefifth physical page address PPN5 of the second memory block BLK2 and theseventeenth logical page address LPN17 is released. As described withreference to the operation S340 of FIG. 6, the table manager 129 canrenew the interval table IT so that the seventeenth logical page addressLPN17 corresponding to the second memory block BLK2 is released.

As a virtual valid of the fifth physical page address PPN5 of the secondmemory block BLK2 is released, the table manager 129 can restore a validcount VCNT of the second memory block BLK2 may be to an original valueOV.

After the third memory block BLK3 is erased, data may be programmed inthe third memory block BLK3. The time that the third memory block BLK3is programmed is not limited and thereby “don't care” is illustrated inthe first and second tables T1 and T2.

Referring to FIG. 9, the memory controller 120 can collect informationof memory blocks (or other erase units like sub blocks) being eraseduntil the sixth interrupt signal INT6 is generated after the fifthinterrupt signal INT5 is generated. For example, the second memory blockBLK2 may be erased before the sixth interrupt signal INT6 is generatedafter the fifth interrupt signal INT5 is generated. As described withreference to FIGS. 10 and 11, the third memory block BLK3 may be erasedafter data stored in the third memory block BLK3 becomes invalid.

In response to the sixth interrupt signal INT6, the table manager 129can renew the tables 131. For example, as described with reference tothe operation S210 of FIG. 5, the table manager 129, as the secondmemory block BLK2 is erased, can set a virtual mapping of the secondmemory block BLK2 to the second table T2. The table manager 129 canincrease a valid count VCNT of the second memory block BLK2 by ‘1’ inthe first table T1.

As described with reference to the operation S320 of FIG. 6, the tablemanager 129 can register a logical page address of an OORA (out-of-rangearea) related to the second memory block BLK2 in the interval table ITtogether with an initial count. For example, a new logical page address(for example, LPN21) or a logical page address (for example, LPN17)previously allocated may be virtually mapped to at least one physicalpage address among the physical page addresses PPN5˜PPN8 of the secondmemory block BLK2.

As described with reference to the operation S325 of FIG. 6, the tablemanager 129 can reduce a count of the eighteenth and nineteenth logicalpage addresses LPN18 through LPN20 related to the first, third andfourth blocks BLK1, BLK3 and BLK4 registered in the interval table IT.As a count of the eighteenth and nineteenth logical page addresses LPN18and LPN19 reaches ‘0’, as described with reference to the operation S325of FIG. 6, the table manager 129 can release virtual mappings of thefirst and fourth memory blocks BLK1 and BLK4 from the second table T2.The table manager 129 can renew the first table T1 so that valid countsVCNT of the first and fourth memory blocks BLK1 and BLK4 are restored toan original value OV. As described with reference to the operation S340of FIG. 6, the table manager 129 can release the eighteenth andnineteenth logical page addresses LPN18 and LPN19 related to the firstand fourth memory blocks BLK1 and BLK4 from the interval table IT.

As described above, the memory controller 120 sets the erased memoryblock BLK as a virtual valid by virtually mapping a physical pageaddress PPN of the erased memory block to a logical page address LPN.

The memory controller 120, as a desired (and/or alternativelypredetermined) time interval (for example, a period) has elapsed by thedesired (and/or alternatively predetermined) number of times, releases avirtual valid. Thus, an erase of an erase-prohibited memory block BLK isallowed.

According to example embodiments of inventive concepts, the erasedmemory block BLK is erase-prohibited for the critical time TCR. Thus, anoperating method of a storage device having improved reliability isprovided. A critical time TCR may be determined by an initial countvalue being defined according to the operation method of FIG. 2. Forexample, the critical time TCR may be the product of the initial countvalue and a period at which the interrupt signals INT1˜INT6 aregenerated.

FIG. 19 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.Referring to FIGS. 1, 3, 4 and 19, in an operation 5410, the memorycontroller 120 programs memory cells of the nonvolatile memory 110. Inan operation S420, the memory controller 120 prohibits an erase of theprogrammed memory cells for the critical time TCR2.

A time interval until the memory cells of the nonvolatile memory 110 areerased after they are programmed is shorter than the critical time TCR2,a problem that reliability of the memory cells is degraded may occur.The storage device 100 in accordance with example embodiments ofinventive concepts improves reliability of the nonvolatile memory 100 byprohibiting an erase of the programmed memory cells MC for the criticaltime TCR2.

The operation S420 may be programmed in the same manner as thatdescribed with reference to FIG. 5 except that an erase operation isreplaced with a program operation. For example, as described withreference to the operation S210, as the memory cells MC are programmed,the memory controller 120 can set at least one page among pages of thememory block BLKa to which the programmed memory cells MC belong as avirtual valid. The table manager 129 can set a virtual valid if thememory block BLK, according to a program order of the memory cells MC ofthe memory block BLKa, upon at least one of programming memory cells(for example, MC1) being programmed first, programming a page beingprogrammed first in pages of the memory cells (for example, MC1) beingprogrammed first, programming memory cells (for example, MC6) beingprogrammed last, programming a page being programmed last in pages ofthe memory cells (for example, MC6) being programmed last, programmingmemory cells MC of a desired (and/or alternatively predetermined) order,and programming a page of a desired (and/or alternatively predetermined)order in pages of the memory cells MC of a desired (and/or alternativelypredetermined) order.

As described with reference to FIG. 6, the memory controller 120 mayprohibit or allow an erase of the memory block BLKa to which theprogrammed memory cells MC belong using the first and second tables T1and T2 and the interval table IT.

As described with reference to FIG. 6, the memory controller 120 can setthe memory block BLKa as a virtual valid by virtually mapping a physicalpage address PPN of the memory block BLKa to which the programmed memorycells MC belong with a logical page address LPN of the OORA(out-of-range area). As a desired (and/or alternatively predetermined)time interval (for example, a period) has elapsed as much as the desired(and/or alternatively predetermined) number of times, the memorycontroller 120 can release a virtual valid. That is, the memorycontroller 120 can prohibit an erase of the memory block BLKa to whichthe programmed memory cells MC belong for a second critical time TCR2.The second critical time TCR2 may be determined according to a secondinitial count value being defined by the operation method of FIG. 19.For example, the second critical time TCR2 may be product of the secondinitial count value and a period at which the interrupt signalsINT1˜INT6 are generated.

The operation method of FIG. 19 is performed in the same manner as theoperation method described with reference to FIGS. 2 through 18 exceptthat an operation of allowing or prohibiting an erase of the erasedmemory block BLK is replaced with an operation of allowing orprohibiting an erase of the memory block BLKa to which the programmedmemory cells MC belong. Thus, an overlapped description thereof isomitted.

FIG. 20 is a flow chart illustrating an operating method of a storagedevice in accordance with example embodiments of inventive concepts.Referring to FIGS. 1, 3, 4 and 20, in an operation 5510, the memorycontroller 120 erases memory cells of the nonvolatile memory 110 andprograms the erased memory cells.

In an operation 5520, the memory controller 120 prohibits an erase ofmemory cells MC for a first critical time TCR1 after the memory cells MCof the nonvolatile memory 110 are erased. The memory controller 120 alsoprohibits an erase of memory cells MC for a second critical time TCR2after the memory cells MC of the nonvolatile memory 110 are erased.

For example, as described with reference to FIGS. 2 through 18, thememory controller 120 can prohibit an erase of the erased memory blockBLKa by mapping a first physical page address of the erased memory blockBLKa with a first logical page address of the OORA (out-of-range area).The memory controller 120 can also prohibit an erase of the memory blockBLKa to which the programmed memory cells MC belong by mapping a secondphysical page address of the memory block BLKa to which the programmedmemory cells MC belong with a second logical page address of the OORA(out-of-range area).

As the first physical page address is mapped with the first logical pageaddress, a valid count VCNT of the erased memory block may increase by‘1’. As the second physical page address is mapped with the secondlogical page address, a valid count VCNT of the memory block to whichthe programmed memory cells MC belong may increase by ‘1’. With thelapse of the first critical time TCR1 after the memory block BLKa iserased, a valid count VCNT of the memory block BLKa may decrease by ‘1’.With the lapse of the second critical time TCR2 after the memory cellsMC of the memory block BLKa are erased, a valid count VCNT of the memoryblock BLKa may decrease by ‘1’. When a valid count VCNT of the memoryblock BLKa has an original value OV, an erase of the memory block BLKamay be allowed.

An operation of prohibiting an erase of the erased memory block BLKa andan operation of prohibiting an erase of the memory block BLKa to whichthe programmed memory cells MC belong may be performed independently ofeach other.

FIG. 21 is a block diagram illustrating a memory controller inaccordance with example embodiments of inventive concepts. Referring toFIG. 21, the memory controller 120 includes a bus 121, a processor 122,a RAM 123, an error correction block 124, a host interface 125, a buffercontrol circuit 126, and a memory interface 127.

The bus 121 is configured to provide a channel between constituentelements of the memory controller 120.

The processor 122 can control an overall operation of the memorycontroller 120 and perform a logical operation. The processor 122 cancommunicate with an external host through the host interface 125. Theprocessor 122 can store a second command CMD2 or a second address ADDR2being received through the host interface 125 in the RAM 123. Theprocessor 122 can generate a first command CMD1 and a first addressADDR1 according to the second command CMD2 or the second address ADDR2stored in the RAM 123 and output the generated first command CMD1 andthe generated first address ADDR1 through the memory interface 127.

The processor 122 can output second data DATA2 being received throughthe host interface 125 through the buffer control circuit 126 or storethe second data DATA2 in the RAM 123. The processor 122 can output datastored in the RAM 123 or data being received through the buffer controlcircuit 126 as first data DATA1 through the memory interface 127. Theprocessor 122 can store the first data DATA1 being received through thememory interface 127 in the RAM 123 or output the first data DATA1through the buffer control circuit 126. The processor 122 can outputdata stored in the RAM 123 or data being received through the buffercontrol circuit 126 as the second data DATA2 through the host interface125 or output data stored in the RAM 123 or data being received throughthe buffer control circuit 126 as the first data DATA1 through thememory interface 127.

The processor 122 may be configured to drive the time counter 128 andthe table manager 129. For example, the time counter 128 and the tablemanager 129 each may be embodied in the form of hardware, software orcombinations thereof.

The RAM 123 may be used as an operation memory, a cache memory or abuffer memory of the processor 122. The RAM 123 can store codes andcommands being executed by the processor 122. The RAM 123 can store databeing processed by the processor 122. The RAM 123 may include a SRAM(static RAM).

The error correction block 124 can perform an error correction. Theerror correction block 124 can generate an error correction code (forexample, parity) for performing an error correction based on the firstdata DATA1 to be output to the memory interface 127 or the second dataDATA2 being received from the host interface 125. The first data DATA1and the parity may be output through the memory interface 127. The errorcorrection block 124 can perform an error correction of the receivedfirst data DATA1 using the first data DATA1 and the parity beingreceived through the memory interface 127. The error correction block124 may be included in the memory interface 127 as a constituent elementof the memory interface 127.

The host interface 125 is configured to communicate with an externalhost device under the control of the processor 122. The host interface125 can receive the second command CMD2 and the second address ADDR2from the external host device and exchange the second data DATA2 withthe external host device.

The host interface 125 may be configured to perform a communicationusing at least one of various communication methods such as a universalserial bus (USB), a serial ATA (SATA), a serial attached SCSI (SAS), ahigh speed interchip (HSIC), a small computer system interface (SCSI), afirewire, a peripheral component interconnection (PCI), a PCI express(PCIe), a nonvolatile memory express (NVMe), a universal flash memorydevice (UFS), a secure digital (SD), a multimedia card (MMC), anembedded MMC (eMMC), etc.

The buffer control circuit 126 is configured to control the RAM 130(refer to FIG. 1) under the control of the processor 122. The buffercontroller 126 can write data in the RAM 123 and read data from the RAM130.

The memory interface 127 is configured to communicate with thenonvolatile memory 110 under the control of the processor 122. Thememory interface 127 can transmit the first command CMD1 and the firstaddress ADDR1 to the nonvolatile memory 110 and exchange the first dataDATA1 and a control signal CTRL with the nonvolatile memory 110.

The RAM 130 may not be provided to the storage device 100. That is, thestorage device 100 may not have a separate memory in the outside of thememory controller 120 and the nonvolatile memory 110. The buffer controlcircuit 126 may not be provided to the memory controller 120. A functionof the RAM 130 may be performed by the internal RAM 123 of the memorycontroller 120.

The processor 122 can control the memory controller 120 using codes. Theprocessor 122 can load codes from a nonvolatile memory (for example,read only memory) being provided to the inside of the memory controller120. The processor 122 can load codes being received from the memoryinterface 127.

The bus 121 of the memory controller 120 may be divided into a controlbus and a data bus. The data bus may be configured to transmit data inthe memory controller 120 and the control bus may be configured totransmit control information such as a command and an address. The databus and the control bus can be separated from each other and may notinterfere with or affect each other. The data bus may be connected tothe host interface 125, the buffer control circuit 126, the errorcorrection block 124 and the memory interface 127. The control bus maybe connected to the host interface 125, the processor 122, the buffercontrol circuit 126, the RAM 123 and the memory interface 127.

According to example embodiments of inventive concepts, after memorycells are erased, an erase of the erased memory cells is prohibited forCTR1. Also, after memory cells are programmed, an erase of theprogrammed memory cells is prohibited for CTR2. Thus, the memory cellsare stabilized and an operation method of a storage device havingimproved reliability is provided.

Although a few example embodiments of inventive concepts have been shownand described, it will be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of inventive concepts, the scope of which isdefined in the appended claims and their equivalents. Therefore, theabove-disclosed subject matter is to be considered illustrative, and notrestrictive.

What is claimed is:
 1. An operation method of a storage device includinga nonvolatile memory and a memory controller configured to control thenonvolatile memory, the operation method comprising: erasing memorycells of the nonvolatile memory using the memory controller; andprohibiting an erase of the erased memory cells for a critical timeusing the memory controller.
 2. The operation method of claim 1, whereinthe prohibiting the erase of the erased memory cells for the criticaltime includes: setting at least some memory cells among the erasedmemory cells to store valid data; managing a table to indicate validdata is stored in the at least some memory cells; and releasing the atleast some memory cells after the critical time has elapsed.
 3. Theoperation method of claim 2, wherein the memory controller is configuredto select the memory cells as an erase target when valid data is notstored in the memory cells.
 4. The operation method of claim 1, whereinthe prohibiting the erase of the erased memory cells for the criticaltime includes: collecting information of memory blocks being erasedamong memory blocks of the nonvolatile memory; and periodicallyregistering the information collected in a slot of an interval tabletogether with an initial count according to a period, wherein each ofthe erased memory blocks is virtually set to store valid data.
 5. Theoperation method of claim 4, wherein the prohibiting the erase of theerased memory cells for the critical time further includes: periodicallyreducing counts corresponding to the slots of the interval tableaccording to the period.
 6. The operation method of claim 5, wherein theprohibiting the erase of the erased memory cells for the critical timefurther includes: periodically releasing information of a slot having acount which reaches a threshold value among the slots of the intervaltable according to the period.
 7. The operation method of claim 5,wherein the prohibiting the erase of the erased memory cells for thecritical time further includes: periodically releasing virtual settingsof memory blocks corresponding to a slot having a count which reaches athreshold value among the slots of the interval table according to theperiod.
 8. The operation method of claim 4, wherein the prohibiting theerase of the erased memory cells for the critical time further includesmapping at least a part of physical addresses of each of the erasedmemory blocks to a logical address of an out-of-range area of a logicaladdress of the storage device.
 9. The operation method of claim 4,further comprising: storing the interval table in the nonvolatile memorybefore power-off.
 10. The operation method of claim 9, furthercomprising: reading the interval table from the nonvolatile memory whenpower is turned on.
 11. An operation method of a storage deviceincluding a nonvolatile memory and a memory controller configured tocontrol the nonvolatile memory, the operation method comprising:programming memory cells of the nonvolatile memory using the memorycontroller; and prohibiting an erase of the programmed memory cells forcritical time using the memory controller.
 12. The operation method ofclaim 11, wherein the prohibiting the erase of the programmed memorycells for the critical time includes: setting at least some memory cellsamong the programmed memory cells to store valid data; managing a tableto indicate valid data is stored in the at least some memory cells; andreleasing the setting of at least some memory cells after the criticaltime has elapsed.
 13. The operation method of claim 11, wherein theprohibiting the erase of the programmed memory cells for the criticaltime includes: collecting information of memory blocks being programmedamong memory blocks of the nonvolatile memory; and periodicallyregistering the information being collected in a slot of an intervaltable together with an initial count according to a period, wherein eachof the programmed memory blocks is virtually set to store valid data.14. The operation method of claim 13, wherein the collecting theinformation of memory blocks being programmed includes: collectinginformation of memory blocks in which last memory cells are programmedaccording to a program order of each memory block.
 15. The operationmethod of claim 13, wherein the collecting the information of memoryblocks being programmed includes collecting information of memory blocksin which first memory cells are programmed according to a program orderof each memory block.
 16. An operation method of a storage deviceincluding a nonvolatile memory and a memory controller configured tocontrol the nonvolatile memory, the nonvolatile memory including aplurality of memory cells, the operation method comprising: erasing thememory cells in one of a plurality of erase operation units of thenonvolatile memory using the memory controller; and at least one of:excluding the memory cells in the one of the plurality of eraseoperation units as an available erase target for a critical period oftime using the memory controller, the critical period of time beingbased on a time elapsed since the memory cells in the one of theplurality of erase operation units were last erased, and programming atleast some of the memory cells in the one of the plurality of eraseoperations units and inhibiting the memory cells in the one of theplurality of erase operation units from being erased for a criticallength of time using the memory controller, the critical length of timebeing based on a time elapsed since the at some of the memory cells inthe one of the plurality of erase operation units were last programmed.17. The operation method of claim 16, wherein the memory cells in thenonvolatile memory are organized into a plurality of blocks, the memoryblocks each include a plurality of physical pages, the at least one ofexcluding the memory cells in the one of the plurality of eraseoperation units as the available erase target and programming at leastsome of the memory cells in the one of the plurality of erase operationunits and inhibiting the memory cells in the one of the plurality oferase operation units from being erased from the critical length of timeincludes, managing a table using the memory controller that maps logicalpage addresses to the physical pages of the plurality of memory blocks,mapping a virtual page to at least one of the physical pages included inthe one of a plurality of erase operation units of the nonvolatilememory after the erasing the one of a plurality of erase operation unitsof the nonvolatile memory, removing the virtual page mapping to the atleast one of the physical pages included in the one of the plurality oferase operation units if one of the critical period of time and thecritical length of time has elapsed since the mapping the virtual page,and prohibiting the at least one of the plurality of erase operationunits from being erased using the memory controller if any one of thephysical pages included in the at least one of the plurality of eraseoperation units is mapped to the virtual page.
 18. The operation methodof claim 16, wherein the at least one of excluding the memory cells inthe one of the plurality of erase operation units as the available erasetarget for the critical period of time using the memory controller andprogramming the at least some of the memory cells in the one of theplurality of erase operations units and inhibiting the memory cells inthe one of the plurality of erase operation units from being erased forthe critical length of time using the memory controller is the excludingthe memory cells in the one of the plurality of erase operation units asthe available erase target for the critical period of time using thememory controller.
 19. The operation method of claim 16, wherein the atleast one of excluding the memory cells in the one of the plurality oferase operation units as the available erase target for the criticalperiod of time using the memory controller and the programming the atleast some of the memory cells in the one of the plurality of eraseoperations units and inhibiting the memory cells in the one of theplurality of erase operation units from being erased for the criticallength of time using the memory controller is the programming the atleast some of the memory cells in the one of the plurality of eraseoperations units and inhibiting the memory cells in the one of theplurality of erase operation units from being erased for the criticallength of time using the memory controller.
 20. The operation method ofclaim 16, wherein the memory cells in the nonvolatile memory areorganized into a plurality of blocks, each one of the plurality ofblocks includes a plurality of strings, and each one of the stringsincludes a number of the memory cells stacked on top of each other in avertical direction between a ground selection transistor and a stringselection transistor.